Trace metal salt



Patented Nov. '29, 1949 PATENT orrlca Msam TRACE METAL SALT Iosenh a. Dunn. St. can, melt, and M G. Miller, Denvllle, N. 1., alaignors to General Foods Co poration, New York, N. Y., a corporation of Delaware No Drawing. Application June 15, ms, Serial No. ram

13Claima. ((31.99-2) This invention relates to the addition of trace mineral supplements to the normal animal diet (including humans as well as domestic animals and fowls) and more particularly to the incore poration of such supplements in salt and the prevention. of loss thereof from the salt before consumption. This application is a continuation in part of our prior applications Serial Nos. 704,285 and 704,286 filed October 18, 1946, both now abandoned.

A few principal mineral elements make up the greater part of the mineral content of the animal body, including calcium, magnesium, sodium, potassium, phosphorus, sulphur and chlorine. The average'animal 'diet is fairly well supplied period of time. In the case of iodine, this loss has been generally attributed to oxidation resulting in liberation of free. iodine, but iodine conwith these principal mineral elements. However,

other dietary minerals are utilized in very small amounts as compared with the principal mineral elements so that they are commonly referred to as "trace elements," and it is well known that the normal animal diet often fails to supply even the very small daily requirements of certain of these trace elements. The dietary supplements required'to meet such deficiencies may vary from time to time and from place to place as the constitution of the normal diet varies.

tinues to be lost'in spite of the most efl'ective.

measures that can be devised to prevent oxidation (see for example Hart Patent No. 2,144,150, Shumaker et al. Patent No. 2,164,089, See Patent No. 2,170,611, Russell Patent No. 2,331,424, and Whitmoyer Patent No. 2,382,193). Furthermore, the some loss has been observed in the case of nonvolatile and non-oxidizable trace elements such as trace metals.

We have discovered that the above mentioned losses are due in large part, if not entirely, to solution of the traceelement compounds used in water or salt brine and actual leaching out of the compounds from the salt mass. Although salt is a very advantageous medium from the above standpoints for incorporating trace element supplements in the diet, it is also very hygroscopic and absorbs large amounts of moisture Accordingly the addition of trace element suption. When such very small amounts of trace.

element supplements are simply mixed with the far larger volumes of food normally consumed, it

is diflicult to obtain uniform administration to 1 individuals. However, salt is a universal constitu ent of the animal diet which is consumed in small but fairly constant daily rations, and for these. reasons is an excellent medium for incorporating trace element supplements in the diet. The desired supplements are simply mixed with the salt in proportions that will furnish appropriate amounts of minerals, taking into account the requirements of the animal and the daily ration..-

of salt consumed. Because the daily consumption of salt is small, the much smaller ration of trace element supplement may amount to as much as 2-3% by weight of the salt in some cases, although usually it will be less than 1%.

Thus it has been proposed to add trace element supplements to salt for use on the table or in the kitchen or for feeding animals, especially iodine in the form of potassium iodide. In many infrom the atmosphere. As moisture continues to ,be absorbed by the salt, water or salt brine gradually percolates through the salt mass and collects at or drips from the bottom of the mass. The trace element compounds are present only in very small amounts and moreover are admixed in finely divided form with the salt so that they are I distributed as small particles on the surfaces of the salt crystals andconstitute a' sort of external phase which tends to be preferentially dissolved. Under these conditions, the small amounts of trace element compounds are rapidly dissolved, even though they may be only very sparingly soluble in water'or salt brine.

Such percolation of moisture with the effects described above takes place not only in loose salt but even in the salt blocks which are placed at suitable points as salt licks for cattle and other animals, as for example in feeding sheds, in the open near feeding or watering places, or often on stakes in the open iield. The blocks, usually in lb. sizes, are conventionally made by compressing ordinary salt under pressure of the order of ten tons per square inch, resulting in dense solid masses that are practically vitreous in character and apparently are substantially impervious. However, their density is not equal to the density of solid crystalline salt, the specific gravity of which is 2.16 whereas the specific gravity of salt blocks is 2.02 plus or minus depending on the pressure used and the crystalline character of the salt. Thus the blocks contain about 7% of void spaces and to "this extent are porous or capillary in nature. We have found that moisture deposited and/or absorbed at the surface of such a block gradually diffuses or percolates throughout the block under the influence of capillary action and gravitation.

The percolating moisture first dissolves both salt and trace elements compounds from the surface layer of the mass of salt and, as the solution percolates inwardly and downwardly through the mass, its concentration of both trace element, compound and salt progressively increases until it passes out of the bottom. Percolation takes place under humid conditions regardless of whether the salt is exposed to light and/or rain or not; in other words, the same loss of trace elements occurs during storageof the salt in the dark in a humid warehouse or the like, particularly if the relative humidity of the surrounding atmosphere is above the critical range for'salt of 70-75%. The surface layer of salt is first very rapidly depleted of trace elements which migrate bothtoward the center of the salt mass and toward its bottom. The zone of surface depletion steadily increases in depth and the concentration of trace elements in the interior first rises and then rapidly falls as the /trace element compounds are lost by escape of the percolating solution from the bottom of the mass.

Thus complete depletion of a 50 lb. salt block may occur within 30 to 60 days simply by exposing it to a humid atmosphere, and this depletion is quite independent of illumination or exposure to sunlight. More important, however, is the fact that practically complete depletion of the surface layer may take place within a very few days, after which animals licking the block get nothing but salt because the rate 'of consumption of the block is seldom if ever as great as the rate of increase in depth of the depleted surface zone. It makes no difference how much trace element is retained in the center of the block if there is none in the surface layer licked by the animal.

The same loss of trace elements occurs even more rapidly in the case of masses of loose salt because of the greater porosity of the mass and the relative ease with which moisture may enter and percolate through the mass. In this case the effect of surface depletioncan be reduced by stirring or agitating the mass, but this is not feasible during storage and is seldom practiced once the salt is placedin the feed trough for the animals. Even in the ordinary salt shaker or open salt cellar used in the kitchen or on the table, it is a common experience in damp. humid weather to find drops of water or brine or crusted salt adhering to the shaker or cellar, usually at the bottom of the salt mass. Trace element compounds originally distributed throughout the salt become concentrated in such liquid phases and to a large extent remain'in the shaker or cellar when salt is removed therefrom.

The chief object of the present invention is to prevent such losses of trace element supplements and to maintain the compounds in uniform admixture with the salt regardless of the conditions to which it may be exposed so that the intended supplementation of the diet is secured as the salt is gradually consumed.

The present application is directed to a particular group of trace metals that are frequently desirable as dietary supplements, this group consisting of copper, manganese, cobalt and iron.

Reference is made to our copending applications Serial Nos. 33,223, 33,224, and 33,225 filed concur rently herewith and directed to supplementation of the diet with other supplemental minerals.

We avoid depletion of the above trace metals due to percolating moisture by the use of trace metal compounds that are substantially insoluble in the moisture taken up by the salt and in the brine solution resulting from percolation of this moisture through the salt. complete insolubility is not necessary, the limiting conditionbeing that the ratio of solubility of the compound in water containing 0-26% NaCl to the solubility of salt in water should not be substantially greater than the original ratio of said compound to the salt. As previously indicated, the amount of each trace 'metal compound will usually be less than 1%,

although in special cases 2-3% may be used. The ratio of solubilities must be limited accordingly. If this limiting value is exceeded, the trace metal compound will be dissolved and lost at greater rate than the salt and depletion will take place, beginning in the surface layer of the salt as stated above. If the limiting value is maintained, however, the proportion of compound to salt, particularly in the surface layer of the salt, will remain unchanged although of course there will be a gradual loss in total weight of the salt mass. At less than the limiting value of the solubility ratio, on the other hand, the proportion of trace metal compound to salt will increase somewhat not only in the mass as a whole but also at its surface. I

It will be understood that such insolubility in water containing 0-26% NaCl must be coupled with a substantial degree of solubility in the digestive fluids found in the gastro-lntestinal tract of the animal, in order that the trace metal itself may become available to the animal during digestion.

The relative solubilities of a particular trace metal compound in brine and of salt in water may be ascertained from known data or determined by experiment if such data are not available. In this connection, it is known that the solubility of a substance in a solution is a'function of the concentration of other substances in the solution. It is also known that the dispersibility of colloidal material in a solution is a function of the amount of electrolyte present in the solution. These two phenomena are highly important factors in the present invention because the moisture taken up by the salt and percolating through it may vary in salt concentration from zero to saturation (i. e., 0-26%). Some compounds increase in solubility in salt brine as the salt content increases while others decrease in solubility, being more soluble in pure water. still others exhibit their maximum solubility or dispersibility at intermediate salt concentrations. For the purposes of the present invention, the compounds used should be substantially insoluble and non-dispersible (i. e., non-peptizable in the true colloidal sense) in water containing 0-26% salt.

Instead of ascertaining relative solubilities, a

simple method of determining whether the desired conditions will be obtained with any given compound is to analyze the drip from a test sample held in an atmosphere of high humidity. As long as the proportion of trace metal compound to salt in the drip does not exceed substantially the original proportion of said compound to salt in the test sample, the retention of the trace metal in the salt is satisfactory.

In usin this testing method, we have found it satisfactory to employ the following procedure. Small test blocks (approximately gm. in weight) were formed with a laboratory hydraulic press applying pressures equivalent to those used in the commercial production of salt blocks. A series of these small blocks were suspended over suitable test tubes and exposed to a relative humidity of 90% or higher for 43 hours after which the blocks and the respective samples of drip collected in the test tubes were analyzed for their salt and trace metal content. For convenience the results of these analyses were expressed in terms of the percentage of the orig inal content of trace metal compound remaining in the test block, 100% retention meaning that none of the trace metal was lost in the drip.

Under the above test conditions, the salt loss from a test block will vary from 5% to Hence retention figures in the range 90-95% refiect equal rates of loss of trace metal and salt. In other words, the proportion of trace metal to salt in the block after the test and also in the drip is the same as in the original block. Retention values above 90-95% indicate loss of salt at a faster rate than trace metal and a consequent increase in concentration of the metal in the block. On the other hand, retention values of less than 90-95%, particularly those less than 85%, indicate that the trace metal 'isbeing lost at a sufllciently faster rate than the salt to result in undesirable depletion of the metal from the salt.

We have correlated results obtained in such rapid retention tests with practical experience when 50 lb. cattle blocks are held in damp warehouses or exposed in the field, and have determined that when retention values'of about 85% and higher are obtained with the rapid retention test, the corresponding commercial blocks are effectively stabilized against loss of trace metal compounds. We have also demonstrated that when retention values of 95-100% are obtained with the rapid retention test, the corresponding commercial blocks when stored in damp warehouses or exposed in the field will actually increase in their proportion of the trace metal compound because the salt is preferentially dissolved. This increase is particularly evident at the surface of the block where the trace metal compound is immediately available to the animal at' all times.

In case the trace metal supplement is to be incorporated in loose salt, the foregoing test procedure can be simplified and at the same time brought into closer conformity with practical conditions by suspending a small mass of the loose salt in a bag or on a screen which allows passage of the drip. Preferably the bag or screen should be of material that does not absorb appreciable amounts of the percolating solution, as otherwise retention of salt and/or trace metal compound in the material may complicate the analysis.

The useful compounds of the above trace metals are subject to the three basic requirements mentioned above, namely, that they are edible (i. e., non-toxic), that they are soluble in the digestive tract, and that they, are substan-v tially insoluble in water containing 0-26% salt. Within these limitations, however, many different types of compounds of the-above trace metals will be found suitable. For example, suitable types of inorganic compounds are the carbonates, hydroxides and oxides, although a number of other miscellaneous inorganic compounds may be used. In the case of iron, ferric hydrate may be formed in the salt by adding reduced iron. Various sulphides may also be used as for example the mineral sulphides troilite (FeS) and alabandite (MnS). Certain organic compounds of these trace metals are also satisfactory, such as the soaps of higher fatty acids. It will be evident that the compound used may include more than one supplemental mineral, as for example, the combination of a trace metal and a trace halogen such as iodine. The followin: are listed as examples in the case of the trace metals 'of the above group:

Cobaltous carbonate Cobaltous basic carbonate Cobaltous hydroxide Cobaltic hydroxide Cobaltous oxide Cobaltic oxide Cobalt silicide Cobalt stearate Cobalt oleate Cobalt linoleate Cobalt palmitate Cobalt behenate Cobalt arachidate Basic copper carbonate Cuprous carbonate Cuprous hydroxide Cupric hydroxide Cuprous o'xide Cupric oxide Cupric stearate i Cupric palmitate Cupric behenate Cupric arachidate Basic ferric acetate Ferrous carbonate Ferrous hydroxide Ferric hydroxide Ferrum reductum Ferrous oleate Ferrous stearate Ferrous palmitate Ferrous behenate Ferrous arachidate Ferrous oxide Ferric pyrophosphate Ferric orthophosphate Sodium iron pyrophosphate Troilite (FeS) Manganous carbonate Manganous hydroxide Man anic hydroxide Manganous oxide Manganous-manganic oxide ,1 Manganic sesquioxide Manganese dioxide Manganous pyrophosphate Alabandite (MnS) Assuming that all of the trace metals of the above group are to be used, the following formula is suitable in the average case:

Per cent Basic copper carbonate 0.10 Manganous carbonate 0.35 Cobalt carbonate 0.01 Reduced iron 0.10 Salt (NaCl) sufficient to make Assuming that all or the trace metals of the aseareo above group are to be incorporated in a block, the

following formula may be used:

' Per cent Cobaltous carbonate 0.05 Manganous carbonate 1.00 Basic copper carbonate 0.75 Ferric hydroxide 0.20 Salt (NaCl) Sumc'ient to make 100 It will be understood that the particular trace metal compounds that are listed in the above formulae are only by way of example and that any other suitable compounds can be substituted therefor. Also-the amounts of the trace metal compounds given in the formulae are based on the amounts of the trace metals per se that are desired in the animal diet, and where other compounds are substituted they should be used in amounts determined on the same basis; On the other hand, the amount of any particular trace metal that is needed will depend upon the normal constitution of the animal diet in the region where the salt is to be used. Hence the'proportions of trace metal compounds given above are subject to considerable variation, but will usually be less than 1%. In special circumstances as much as 3% may be desirable, as indicated for example in the case of certain poultry requirements for manganese. It may also be desirable to vary the constitution of the salt mass by omitting certain of the trace metals listed in the above formulaaand of course other trace mineral supplements may be added if desired.

In the case of salt blocks, it is often desirab to color the supplemented blocks to distinguish them from ordinary blocks. The trace metal compounds themselves may provide sufficient coloring for this purpose; for example, the above formula produces a dark reddish color. Lazurite, which is a source of nutritional sulphur, produces a blue color. Pigments may be added if desired, and different colors 'may be used to dif ferentiate blocks of varying composition.

In controlling deficiency diseases by dietary supplements, one of the major problems is to secure approximately uniform administration of "such supplements to individual animals because of the very small amounts needed, the practical difliculty of distributing such small amounts uniformly throughout feed mixtures, etc. It will be seen that'salt embodying the present invention eliminates such difliculties and provides a very convenient and practical means of administering trace elements to animals in uniform controlled amounts. The consumption of salt by an animal such as a cow, for example, will be reasonably uniform in amount depending on the daily requirement of the animal and is not materially affected by the presence of a small proportion of supplementary materials. The present invention makes it possible to disperse such materials throughout a mass of salt in definite uni--' form concentration, although they are present in amounts as small as a fraction of a per cent in.

8 administration may be desirable even though" there is no deficiency in the normal animal diet.

For example, it has been found the production of milk and butter fat can be increased by the temporary administration of thyro-protein (e. 1., iodinated casein) in amounts substantially above the normal requirements of the. animal. This administration can be effected simply and controlled accurately by the use of salt containing appropriate amounts of thyro-protein either alone or in combination with other trace mineral supplements that may be desired. Excessive amounts of trace metal supplements may be administered in the same manner whenever desired.

It will be understood from what has been said; above that the invention in its broad aspect is not restricted to any particular trace metal 01 the above group or to any particular combination thereof, since the choice of those to be used will depend on the constitution of the normal diet and will vary in different regions. In the case of any particular trace metal of this, group,

claims for a definition of the limits of the iiivention.

What is claimed is:

1. Salt containing a trace metal supplement to the animal diet and of the type having dispersed therethrough an edible compound of a trace metal of the group consisting of copper,

manganese, cobalt and iron, said compound being substantially soluble in digestive fluids whereby said trace metal is made available to the animal during digestion but substantially insoluble in water containing 0-26% salt sothat it is not dissolved by moisture absorbed by and percolating through the salt. I

2. Salt containing a trace metal supplement to the animal diet and of the type having dispersed therethrough not more than 3% of an edible compound of a trace metal of the group 4 consisting of copper, manganese, cobalt and iron,

said compound being substantially soluble in digestive fluids whereby said trace metal is made available to the animal during digestion but the ratio of the solubility of said compound in water containing 0-26% salt to the solubility of salt in water bein maximally substantially equal to the ration of the proportion of said compound to the proportion of salt.

3. A salt block containing a trace metal supplement to the animal diet and of the type comprising a dense solid mass of compressed salt having dispersed therethrough an edible compound of a trace metal of the group consisting of copper, manganese, cobalt and iron, said compound being substantially soluble in digestive fluids whereby said trace metal is made available to the animal during digestion but substantially insoluble in water containing 0-26% salt so that y it is not dissolved by moisture absorbed by and plement to the animal diet and of the type com prising a dense solid mass of compressed salt having dispersed therethrough not more than 3% of an edible compound of a trace metal of the group consisting of copper, manganese, cobalt and iron, said compound being substantially soluble in digestive fluids whereby said trace metal is made available to the animal during digestion but the ratio of the solubility of said compound in water containing -26% salt to the solubility of salt in water being maximally substantially equal to the ratio of the proportion of said compound to the proportion of salt in the block.

5. Salt having dispersed therethrough not more than 3% of a copper supplement to the animal diet in the form of an edible copper compound that is substantially soluble in digestive fluids whereby copper is made available to the animal during digestion, the ratio of the solubility of said compound in water containing 0-26% salt to the solubility of salt in the water being maximally substantially equal to the ratio of the proportion of said compound to the proportion of salt.

6. Salt having dispersed therethrough not more than 3% of a manganese supplement to the animal diet in the form of an edible manganese compound that is substantially soluble in digestive fluids whereby manganese is made available to the animal during digestion, the ratio of the solubility of said compound in water containing 0-26% salt to the solubility of salt in water being maximally substantially equal to the ratio of the proportion of said compound to the proportion of salt.

'7. Salt having dispersed therethrough not more than 3% of a cobalt supplement to the animal diet in the form of an edible cobalt compound that is substantially soluble in digestive fluids whereby cobalt is made available to the animal during digestion, the ratio of the solubility of said compound in water containing 0-26% salt to the solubility of salt in water being maximally substantially'equal to the ratio of the proportion of said compound to the proportion of salt.

' 8. A salt block containing a copper supplement to the animal diet and of the type comprising a dense solid mass of compressed salt having dispersed therethrough an edible copper compound that is substantially soluble in digestive fluids whereby copper is made available to the animal during digestion but is substantially insoluble in water containing 13-26% salt so that it is not dissolved by moisture absorbed by and percolating through the block.

9. A salt block containing a manganese supplement to the animal diet and of the type comprising a dense solid mass of compressed salt having dispersed therethrough an edible manganese compound that is substantially soluble in digestive fluids whereby manganese is made available to the animal during digestion but is substantially insoluble in water containing 0-26 salt so that it is not dissolved by moisture absorbed by and percolating through the block.

10. A salt block containing a cobalt supplement to the animal diet and of the type comprising a dense solid mass of compressed salt having dispersed therethrough an edible cobalt compound that is substantially soluble in digestive fluids whereby cobalt is made available to the animal during digestion but is substantially insoluble in water containing 0-26% salt so that it is not dissolved by moisture absorbed by and percolating through the block.

11. A salt block for feeding animals having not more than 3% basic copper carbonate dispersed therethrough.

12. A salt block for feeding animals having not more than 3% manganous carbonate dispersed therethrough.

13. A salt block for feeding animals having not more than 3% cobalt carbonate dispersed there through.

JOSEPH A. DUNN. FRANK G. MILLER.

REFERENCES oI'rEn The following references are of record in the file of this patent:

UNITED STATES PATENTS McHan July 2, 1946 

